Counterbore



2 Sheets-Sheet 1.

(No Model.)

A. LATHAM. UOUNTERBORE, REAMER,. 0R GOUNTEBSINK. No. 370,484.

Patented Sept. 2'7,

MWMW W a J/Q (No Model.) 2 Sheets-Sheet? A. LATHAM. GOUNTBRBORB, REAMER,0R GOUNTERSINK.

Patented Sept. 27, 1887.

UNITED STATES PATENT Enron.

ALB vRT LA'IClElAM, OF TVALIHAM, MASSACHUSETTS.

GGUNTERBORE, REAMER, OR CQUNTERSINK.

EPISCIPICATION forming part of Letters Patent No. $70,489:, datedSeptember 27, 1887.

Application filed August 31, 1885. Serial No. 175,818. (No model.)

To alt whom it may concern: W Be it known that I, ALBERT LATHAM, ofWaltham, in the county of illiddlesex and State of Massachusetts, haveinvented a new and useful Improvement in Oounterbores, Reamers, orOountersinks, which will, in connection with the accompanying drawings,be hereinafter fully described, and specifically defined in the appendedclaims.

This invention relates to counterbores, reamers, or countersinks whichare employed in working metals; and it consists in features of novelty,hereinafter fully described, and pointed out in the claims.

In said drawings, Figure 1 is a side elevation of a tangentialcounterbore. Fig. 2is an edge elevation of the same. Fig. 3 is aninverted or under side plan view of the counterbore shown in Figs. 1, 2.Fig. i is a side elevation of a radial counterbore, viewed as from theright in Fig. 5. Fig. 5 is an elevation of the counterbore shown in Fig.4 and as viewed from the left in that figure. Fig. 6 is an inverted orunder side plan view of the counterbore shown in Figs. 4:, 5. Fig. 7 isa side elevation of a concave-lip tangential counterbore, taken as fromthe left in Fig. 8. Fig. 8 is a side elevation taken as from the rightin Fig. 7. Fig. 9 is an inverted or under side plan view of Figs. 7, 8.Fig. 10 is a view similar to 8, showing by dotted lines the operation ofan emery-wheel in sharpening the teeth of the counterbore, and the teethbeing radial, instead of tangential, as in Fig. 8. Fig. 11 is aninverted or under side plan view of the counterbore shown in Fig. 10.Fig. 12 is a side elevation of a taper reamer embodying my invention.Fig. 13 is a sectional plan view, the section being taken on line as,Fig. 12, and the plan showing the portion below that line. Fig. 14. is aside elevation of a stair-step counterbore embodying my invention. Fig.15 is an inverted or under side plan view of Fig. 14.. Fig. 16 is a sideelevation of a countersink embodying the essential feature of myinvention. Fig. 17 is a plan view of the same, viewed as from the top ofthe sheet in Fig. 16. Fig. 18 is a diagrammatic view showing the end ofa two-lip counterbore as enrolled or extended in a right line, andshowing in parallel lines the paths of the cutter when imparting thefreeing to the ends of the lips. Fig. 19 is a view like Fig. 18, withthe exception that the paths of the cutter, when imparting the free ingto the ends of the lips, are shown in oblique instead of parallel lines.Fig. 20 is a perspective view of a counterbore having three radial lipsformed with an arc-like front face, 0, the same as the correspondingface in Figs. 7, 8, 9, 10, 11. view, the section being taken on line WW, Fig. 20, and the view being as from above that line.

I deem it proper to state as matter of in- Fig. 21 is 'a sectional plan.

troduction that the three essential parts of counterbores are the shanka, by which they are secured in the arbor of the lathe or other tool bywhich they are actuated; the stem 6, which enters the already-formedhole in the body to be counterbored, which stern holds the counterborein proper axial relation to said hole, and the lips A, which perform thecutting, and whose several characteristics will be hereinafter describedin connection with my improvement. Reamers are also formed with a shank,a, and with a series of cutting-lips, A, as shown in Figs. 12, 13, andwith a stem, 12, in case the taper of the cutting portion of the reameris considerable; but the stem is often omitted, especially so if thetaper be but slightly more than the chip to be cut and the cylindricalportion be of considerable length. Countersinks are also formed with ashank, a, and a conical head or body having a series of Quttinglips, A.This tool is formed with its lips converging to a point, and hence stem12 is omitted, the object being that holes having various diameters maybe tapered or countersunk with the same tool; but all said tools have acommon purpose narnely, to enlarge a hole already formed and the onlydifference in them is in the form of such enlargement, as withcounterbores the enlargement of the hole is of uniform diameter, andusually with the flow of such enlargement at right angles to the axis ofthe hole. With reamers the hole may be enlarged in. part or all itslength in taper form, as with the rcamer shown in Fig. 12; or, if thecylindrical portion be of sufficient length and the taper but site sidesat an angle of sixty degrees, in order that the enlargement which theyproduce shall correspond with and receive the usual conical screw-heador for other purposes.

In my application Serial No. 144,005, filed September 25, 1884, forcounterbores, reamers, or countersinks, and manufacture thereof, andfrom which the subject-matter of this application has been eliminatedunder the ruling of the Office requiring division of the application, isshown machinery especially adapted and designed for the manufacture ofthe tools which constitute the subject-matter of this application, andthis specification will be prepared with due reference to said formerapplication and the subject-matter thereof.

For convenience of description the same parts will in all theillustrations, whether of counterbores, reamers, or countersinks", havethe same indicating letters or figures.

Referring again to the drawings, 0' represents the front lineal face ofthe lips A. d is the rear lineal face of the lips. c is the outer orcircumferential face of the lips, and f is the spiral end face of thesame. The cutting-edge g is the acute angle resulting from theintersection of the front lineal face, 0, and spiral end face, f, whilethe retired angle it results from the intersection of the rear linealface, d, and spiral face f.

In order to give the proper freeing or clearance, as it is termed, tocutting-edge g, the face f is cut away rearward from face a by a spiralpath, as is shown in various figures; and one of the essential featuresof my invention consists in cutting said spiral face of each tooth withprecisely the same pitch, in order that as the teeth are sharpened bygrinding upon the front lineal face, 0, they will each remain of thesame length and with their edge g at the same angle to the axis of thebody of the tool. If the lips of the counterbore be radial and the facesa d be in the same plane, as shown in Figs. 1, 2, and the cutting-edgesg are, when the tool is first made, at right angles (or otherwise) tothe axis of shank a and stem 6, and the faces f are identical spirals,then as faces a are ground away to sharpen edges 9 the edge 9 willalways remain at the same angle to the axis, if face 0 be kepttangent-ial, as at first formed; or, if the face 0 be radial from theaxis and the edge 9 be at right angles (or otherwise) to the axis,thenif as face 0 is ground away to sharpen the cuttingedge said face iskept radial the angle of edge 9 to the axis will remain unchanged; andthe same is equally true in relation to the reamers and countersinkswhose front edge, e, is radial, and which is ground away to maintain thecutting-edge g, as with faces f each the same spiral, and with faces 0uniformly ground away and kept radial, the edge of every tooth will havethe same inclination to the axis and each the same projection'from theaxis.

The means and method of forming faces J,

an identical spiral in all the teeth, are fully shown and described inmy said earlier specification.

In Fig. 9 the dotted lines t indicate both the changing positions of thecutting-tool by which spirality is imparted to "faces f, the cuttingcommencing on each lip at line 9, with the counterbore revolving in thedirection indicated by the arrow, the path of the cuttingtool by whichsuch spirality is imparted being indicated in Figs. 18, 19, in theformer of which the cutter moves in parallel paths k, in the linealdirection of the counterbore, but gradually encroaches thereon afterarriving at its end face, (indicated at Z,) until the spiral face ofeach tooth is completed; but instead of moving in parallel paths thecutter may move as shown in Fig. 19, where at each cut the tool moves ina spiral path till the required chip is acquired, when it moves, as inFig. 18, across the face of the lip, all as described in said formerapplication. When the front face, 0, of the teeth is radial, then thecuttingtool, by which the face f is rendered spiral, is arranged asindicated by dotted lines j, as the counterbore revolves, as indicatedby the arrow in Fig. 11, and the reduction of the lips by grinding awayface 0, as stated, will proceed, as indicated by said lines j.

In Figs. 7 to 11 the front face, 0, is formed as an arc of a circle, thelips in Figs. 7, 8, 9 being tangential, while in Figs. 10, 11 they areradial. This form of lip is sharpened by means of a small emery-wheelarranged as indicated at B, Fig. 10, and it gives a free cutting-edge ofany desired acuteness, according as faces 0 f are arranged relatively toeach other.

As a result of forming each face f of the several lips in a tool withidentical spirals, the angle of cutting-edge y will not be changed inrelation to the axis of the tool, as the lips are gradually worn away bygrinding said faces f; and hence whether the enlargement to be producedby the tool be conical or cylindrical, it will at all stages in the lifeof the tool have the same identical angles relatively to the axis of thehole previously formed and which is being thus enlarged.

When the counterbore is formed with a series of steps, as at m a 10,Figs. 14, 15, the tool may be used in connection with differentsizedholes, or it may be employed to form a seat for a screw or bolt having amultiple shouldered head corresponding therewith.

In order that in tangential counterbores,like or similar to thoseshownin Figs. 1,2,the cutting-tool which shapes the spiral face ofthelips may have time after moving across the end face of one lip andarriving at rear face, d, thereof, to be moved to the proper position tocommence at line 0 on the next lip, a slight depression or reduction, t,is formed in stem 12 I next the lips when milling faces 0 d, thus af=fording room to move the cutter in the lineal ICO direction of thecounterbore, after the rear of one lip has passed the cutter and beforeit is encountered by the next,such distance that the cutter will be atthe end face of the lip at the moment that face 0 of the next liparrives at the edge of the cutting-tool; and to facilitate the grindingof stem b, after it has been hardened, in order to bring it to standardsize, a concentric groove, q, is formed therein next the ends of lips A.By forming tangential counterbores with the faces a d at or near a rightangle to each other, as shown in Figs. 7, 8, 9, the counterborepossesses at least three times the amount of life or endurance as whenformed in the usual manner, as shown in uFigs. 1, 2, as is easilydemonstrated by measurement of the peripheral extent or distance betweenlines 0 d of each lip, the extent of such distance being the measure ofendurance or service of the counterbore. Besides this,at every grindingof face 0 the angle of intersection between faces cand eis in its entirelength sharpened, as well as cuttingedge g, thus restoring the desiredsharp angle between faces 0 e.

By reason of my method of producing the backing off or clearance of theend faces, f,the several seats or shoulders formed by a stairstepcounterbore, like that shown in Figs. 14, 15,will be always the samelineal distance each from the other, if the lips are all equally reducedby sharpening, and hence the several shoulders of duplicatemultiple-headed bolts will bear equally upon the several seats or stepsout by the counterbore.

\Vhen the front face, 0, is to be formed as an arc of a circle, as inFigs. 7 to 11, both faces 0 and d will be formed by a rotary cutter ormill, which 13 may indicate, both in form and mode of operation.

It will, from the above description, be ob vious that not only has thefront face, 0, of every lip in a counterbore the same relation to radiallines, and the end faces, f, each the same spirality or pitch, and alsothe same angle relatively to the axis of the counter-bore, but that theedge 9 of every lip will have the same relation to a plane which is atright angles to said axis, so that each edge 9 W111 in use out a chip ofthe same thickness as every other, which result could not beaccomplished if the several foregoing conditions dld not each exist inthe tool, as described and shown.

I claim as my invention- 1. As a new article of manufacture, acounterbore, reamer, or countersink having a plurality of lips, each ofwhich is formed upon its end face,f, in a spiral path identical n pitchwith every other lip, and having sald end face of each lip at the sameangle relatively to the axis as every other lip, hav ing the frontlineal face, 0, of each lip 1n the same relation to radial lines asevery other 11p, and also having the cutting-edge g of every lip in thesame plane, whereby each 11p will cut the same depth of chip, all asspecified.

2. A connterbore having the lips A formed with the front lineal face, 0,as an arc of a circle, and with the rear face, d, in a right line and ata right angle, or nearly so, to face 0, as specified.

3. A stair step counter-bore having its several series or sets of lipsarranged one above the other, as specified, and with each tooth clearedor backed off in a spiral path identical in pitch with each and everyother tooth thereof, and with the front lineal face of each tooth in thesame relation to a radial line as every other. tooth thereof,substantially as specified.

ALBERT LATHAM.

Witnesses:

'1. W. PORTER, ROBERT ASHE.

